mineral resources Flashcards
what is a mineral?
-naturally occurring inorganic solid, with a definite chemical composition
-not made by humans
-never been alive, not made up from plants/animals
-each one made up of particular mix of chemicals
what is the use of mineral resources?
-non-renewable
-they reformed too slowly to be replaced with timescales that would allow human use
-long-term use relies on understanding of scientific methods that will increase supplies, extend use, find alternatives for those in restricted supplies
what is the lithosphere?
-outermost shell of a terrestrial planet or natural satellite. on earth, its composed of the crust and portion of the upper mantle
-includes rocks, solid, mineral resources that are impact for human society
what does hydrothermal mean?
-action of heated water in the earths crust
what does deposition mean?
-laying down of sediment carried by wind, flowing water, the sea or ice
what does alluvial processes mean?
-involves materials being carried and separated by flowing water
what are the types of rock?
-igneous= has crystals
-sedimentary= has grains bound together by a cement
-metamorphic= has crystals
what are igneous rocks?
-if the magma cools slowly underground, theres more time to cool so crystals grow large
-these rocks are called intrusive rocks
-if the magma cools quickly on surface of earths crust theres no time fro crystals to grow so theyre very small
-these rocks are called extrusive rocks
what is hydrothermal deposition?
-igneous intrusions= magma pushes up, cools & solidifies within crust forming batholith
-intrusions produce pressurised superheated water
-dissolves minerals in surrounding rock
-mineral rich solutions travel along fissures away from batholith & cool
-minerals come out of solutions in order of solubility
what is fractional crystalisation?
-as superheated water cools along hydrothermal vents minerals come out of solution
-least soluble crystalise first and deposited in layers in vents
-later explored and extracted
-allows access to minerals that otherwise couldnt be extracted
-minerals include tin, copper, lead, silver, gold, and arsenic
what are sedimentary rocks?
-form from compaction of pre-existing pieces of rock and mineral
-a previous rock must be weathered and eroded, and particles transported and then deposited
-then the grains are compacted, and the pressure binds the loose sediment together to form a rock
what are metamorphic rocks?
-common economically used rocks are slate and marble
-slate was once mudstone or clay that’s been altered by intense heat/pressure
-marble was once limestone which was heated and recrystalised
what are proterozoic marine sediments?
-includes iron ores deposits
-formed when dissolved iron compounds become oxidised by oxygen released from photosynthesis
-produces insoluble iron oxide deposits
-occurred mainly between 2.5 and 2.8 billion years ago
what are biological sediments?
-when mineral deposits form from biological organisms
-this often concentrates the mineral that are then deposited in sedimentary rocks
what are alluvial deposits?
-refer to the movement and separation of materials caused by flowing water
-the velocity of the water dictates the ability of the water to carry solids,and the density of solids that can be transported. humans exploit alluvial deposits including:
*gold
*gravel
*sand
*clay
*diamond
what is stock?
all resources that can be exploited now, in the future, or never
what is a resource?
all materials that are theoretically available, including material that is currently economically unavailable to extract or cannot be extracted either current technology
what is a reserve?
portion of the resource that can be exploited now, economically using existing technology
what are reserves and resources?
-quantity of every metal present in the lithosphere far exceeds realistic human demands
-only a portion of it will ever be exploitable and even less can be exploited economically
what is laskys principle?
as purity of a mineral decreases, the mass of montreal’s present increases exponentially
what is cut off ore grade?
-minimum grade required for a mineral or metal to be economically mined
-material found to be above this grade is ore, material below is waste
-measured in grams per tonne (g/T)
what is inferred reserves?
-presence of mineral has been predicted by knowledge of geological structures but isn’t completely accurate, & not enough to estimate the quantity that can be extracted
what are potable reserves?
sufficient info is available on the minerals so that the quantity can be estimated, proves that further exploration is justified
what are proven reserves?
sufficient exploration has been carried out to get an accurate estimate so the mineral can be extracted
what factors affect mine viability?
-economics
-geology
-chemical form
-ore purity and cut off ore grade
what is ore purity in mine viability?
-purity affects financial costs of exploration, environmental impacts of extraction
-low ore grade means more rock will have to be mined, more waste will be produced, more energy needed for mining, more pollution generated
what is chemical form in mine viability?
-chemical form of minerals affects chemical extraction
-for example:
•aluminium and be extracted from bauxite
•aluminium can’t be extracted from clay, but this is far more abundant
what is geology in mine viability?
-overburden: rock that lies above the mineral deposit, has to be removed before extracting the mineral. hard overburden may require blasting which increases costs. loose overburden may have landslide risks
-hydrology: high precipitation or impermeable rocks may increase drainage costs
-depth: deeper deposits=inc. costs. more rock has to be removed so pumping of ground water may be required
what is economics in mine viability?
-mining must make a profit
-must balance production costs and income
-cut off ore grade changes as tech improves and market prices fluctuate
why must we explore before extracting?
-reserves can’t be extracted until they’re proven
-this requires remote exploratory techniques
-considerations:
•distance from site
•data collection range
•technique
•large or small scale
what is IR spectroscopy?
-different minerals emit infrared radiation at different wavelength and these can be used to identify them
-example: zuinshan mining field
what is gravimetry?
-gravimetry detects variations in gravity caused by variations in density and mass. igneous rocks are usually more dense than sedimentary deposits
-example: hercynian rehemna, Morocco
what is magnetometry?
-magnetometers detect rocks which are more magnetic such as the iron core magnetite and ores of tungsten and cobalt
-example: drone magnetometry, estancias mountain range, Almeria
what are seismic surveys?
-involved sound waves produced by controlled explosions, or a seismic vibrator in the surface, the echoes can give info about the depth, density and d shape of rock strata
-example: flin flon mining camp, Canada
what is resistivity?
-measurement of the difficulty with which electricity passes through a material. in general, sedimentary rocks have lower resistivities than igneous rocks because they have higher water contents
-example: karst regions
what is trial drilling?
-most expensive technique per sampling site but is only method that actually produces samples of the rocks underground
-example: daunia coal mine
what is chemical analysis?
-lab tests confirm the chemical composition and purity of a he minerals in the rock samples
-example: dazhu, China
how can we extract minerals?
-opencast mining or quarrying
-underground mining
-washing out a weak mineral using hoses
how are open cast or underground mining different?
-opencast: overburden is removed and stored around the site- these bunds absorb noise. then the economic mineral is extracted using bulldozers
-underground: also be called deep shaft or adit mining. horizontal tunnels or adits branch off the main shaft. a main shaft is sunk
